1. Field of the Invention
The present invention relates to a method and apparatus for performing multicast/broadcast services.
2. Description of the Related Art
A Multimedia Broadcast/Multicast Service (MBMS) may transfer broadcast and multicast data to multiple users at the same time using shared network resources. This service may save resources in a core network (CN) and a radio access network such as a Universal Terrestrial Radio Access Network (UTRAN) since the same data does not have to be separately sent to each user equipment (UE).
Broadcast services may transmit data to a certain area so that any users in the area may receive the data. In contrast, multicast services may require that the users have subscribed to a multicast service group before receiving the data. The users may possess an encryption key (or similar mechanism) to decipher the received data. The encryption key helps prevent non-subscribed users from receiving the transmission.
The CN may include a network element, such as a MBMS Services Centre (MBMS-SC), that transmits multicast data to serving GPRS Support Nodes (SGSNs) using a multicast Gateway Tunneling Protocol (GTP). The GTP tunnel may be shared with all users under the SGSN. The tunnel may be created only to those SGSNs that have multicast users. When the MBMS-SC/GGSN sends multicast data, it may duplicate the packets and send the packets to all the tunnels. The SGSNs may further create multicast GTP tunnels to radio network controllers (RNCs) that have indicated that they have multicast users in their cells. This sent data may be sent to the RNCs because the data is meant for certain areas and therefore the UEs in this area don""t have to indicate their presence to the RNC. The RNC does not know whether there are any UEs in the cell and therefore no indication may be given to the SGSN by the RNC.
The MBMS may transmit many broadcast and multicast services. Each service may have different QoS parameters. Additionally, the multicast services may be transmitted to different groups of users that receive the service. The multicast GTP tunnels between the MBMS-SC and the SGSN and between the SGSN and the RNC may be separately made for each service.
A method is provided to activate a packet data protocol (PDP) context in a cellular network. This method may include determining whether multicast or broadcast users associated with the cellular network may receive multicast or broadcast data and activating the PDP context based on the determination. The activating may be performed by a Serving GPRS Support Node (SGSN). The activation may be transparent to user equipment. The determination may be based on a trigger. The trigger may occur when a notification is sent to a SGSN. The SGSN may get notified of a status of the multicast or broadcast service based on a periodic status query, an update message or an activation request, for example.
A system is also provided for performing a multicast or broadcast transmission in a cellular network. The system may include a core network node to activate a packet data protocol context based on information of users associated with the cellular network. The core network node may include a SGSN that includes a database related to user information.